Joint sealants of the hot poured type have been used for many years in sealing joints and cracks in Portland cement concrete and asphaltic concrete pavements. Such pavements typically are those existing on the highway, but they may likewise include airfield pavements, parking lot pavements, and bridge decks.
These joint sealing compositions are typically composed of a mixture of materials which will form a resilient and adhesive compound capable of effectively sealing joints in the concrete against infiltration of moisture and foreign material throughout repeated cycles of expansion and contraction with temperature changes and that will not flow from the joint or be picked up by vehicle tires at summer temperatures. The materials are formulated so that they are capable of being brought to a uniform pouring consistency suitable for completely filling the joints without inclusion of large air holes or discontinuities and without damage to the material.
Two specifications have been established for such a concrete joint sealing composition. One is set forth as ASTM D 3405-75-T, which is hereby incorporated by reference. One of the significant tests in ASTM D 3405-75-T is a resilience test in which the recovery shall be a minimum of 60%. The standard specification adopted by the federal government for a concrete joint sealing composition is Federal Specification SS-S-164, which is the same as ASTM designation D 1190-74, both of which are likewise hereby incorporated by reference. The latter specification has a significant test, termed the bond test, in which the sealer is tested at 0.degree. F. (-17.8.degree. C.) for five complete cycles. The development at any time during the test procedure of a crack, separation or other opening that at any point is over 1-1/4" (6.4 mm) deep in the sealer or between the sealer and mortar block shall constitute failure of the test specimen. Additionally, Federal Specification SS-S-164 requires the joint sealer to have a pour point which is at least 20.degree. F. (11.degree. C.) lower than the safe heating temperature, which is the maximum temperature to which the material may be heated without exceeding the permitted flow. The test also requires a penetration at 77.degree. F. (25.degree. C.), 150 g, 5s of 90 or less, and a flow at 140.degree. F. (60.degree. C.) which does not exceed 5 mm.
The present invention provides for an improved joint sealing compositon which has good cold temperature flex, a good elastic recovery, is non-tacky, non-bleeding, and which has a wide temperature range for use with good adhesion to concrete, be it Portland cement type concrete or asphaltic cement. Such composition reliably passes the resiliency test of ASTM D 3405-75-T and the standard Federal Specification SS-S-164 for concrete joint sealers of the hot poured elastic type.
The joint sealer of the present invention comprises the reaction product of a mixture of prescribed amounts of asphalt flux, styrene, and a rubber polymer.